1. Field of the Invention
The invention refers to a method and an apparatus to control coolant flow through an engine, especially for a motor vehicle. The method comprises a coolant heated by the engine and cooled by a radiator wherein coolant flow depends on the number of rotations of the engine. The apparatus has an engine connected to a radiator, a coolant pump arranged near the engine and combined with the radiator and a component forming a coolant circuit wherein a coolant fluid leaves the radiator in direction to the engine, exits the engine and flows through the coolant pump to the radiator.
2. Description of the Background Art
FIG. 2 shows a coolant circuit for an engine used in a vehicle today. A main cooling circuit leads a fluid coolant between the engine 1 and a main radiator 12. A coolant pump 13 moves the fluid coolant which is cooled by the main radiator 12 to the engine 1. Into the engine 1 the fluid coolant absorbs engine heat. The heated fluid coolant is conducted from the engine 1 through a thermostat 14 back to the main radiator 12. A secondary cooling circuit is consisted by a low temperature radiator 15 and a charge-air cooler 16 wherein the heated air left the engine 1 is conducted through the charge-air cooler 16 back to the engine 1. In the charge-air cooler 16 the engine air is cooled by a gaseous coolant which is moved by an electrical pump 17 from the low temperature radiator 15 to the charge-air cooler 16. In the charge-air cooler 16 the gaseous coolant absorbs the heat from the engine air wherein the engine air is cooled. The cooled engine air is conducted back to the engine while the gaseous coolant goes back to the low temperature radiator 15 for cooling.
FIG. 3 shows a schematic diagram of another heat exchanger. A coolant pump 2 is arranged at the engine 1. The fluid coolant left the coolant pump 2 is conducted through the thermostat 3 to the radiator 4. After the coolant is circulated in the radiator 4 it flows back to the engine 1. In another direction heated engine air leaves engine 1 in direction of a heater core 5. Heater core 5 emits heat to a vehicle cabin wherein engine air is cooled down and flows back to the engine 1.
In coolant circuits of motor vehicles coolant pumps are operating depending on engine number of rotations. The coolant pumps running all the time are changing the flow rate of coolant with changing engine number of rotations. During the warm up operation of the engine the coolant flow prolongs the warm up operation. At high engine numbers of rotations the coolant flow is very high. Those coolant flows are often in the saturation for heat exchange and running at high speeds which can lead to cavitations and high pressures on heat exchangers as radiators or heater cores and hoses.